Ecg Extraction Code

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Contents n

ZERO CROSSING REMOVAL

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DETECT R_PEAK

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Calculate R in the actual Signal

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After R Peak Tracking ... DETCET OTHERS

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ONSET

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P Peak

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Q Detection

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S Detection

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T Peak

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END OF T

% Load original 1D signal. clc; clear all; close all; ELEVATED=[]; [fname path]=uigetfile('*.mat'); fname=strcat(path,fname); load(fname ); z=zeros(100,1); A=val(1,:); v1=val(1,:)-val(1,1); A=v1; A=A'; zc=A(1); A=[z;A;z]; % Plot Actual Signal s = A(1:1:400); s = A; ls = length(s); figure(1) plot(s); title('Original Signal'),grid on % Perform decomposition at level 8 of s using db4 [c,l]=wavedec(s,8,'db4'); ca1=appcoef(c,l,'db4',1); ca2=appcoef(c,l,'db4',2); ca3=appcoef(c,l,'db4',3); ca4=appcoef(c,l,'db4',4); ca5=appcoef(c,l,'db4',5); ca6=appcoef(c,l,'db4',6); ca7=appcoef(c,l,'db4',7); ca8=appcoef(c,l,'db4',8); %Plot the coefficient figure(2) plot(c),title('decomposed signal'),grid on figure(3) subplot(4,2,1)

plot(ca1),title('1st subplot(4,2,2) plot(ca2),title('2nd subplot(4,2,3) plot(ca3),title('3rd subplot(4,2,4) plot(ca4),title('4th subplot(4,2,5) plot(ca5),title('5th subplot(4,2,6) plot(ca6),title('6th subplot(4,2,7) plot(ca7),title('7th subplot(4,2,8) plot(ca8),title('8th

level approximation'),grid on Generated by Foxit PDF Creator © Foxit Software

http://www.foxitsoftware.com For evaluation only. level approximation'),grid on level approximation'),grid on level approximation'),grid on level approximation'),grid on level approximation'),grid on level approximation'),grid on level approximation'),grid on

% Extract detail coefficients at levels % 1, 2 and 3, from wavelet decomposition % structure [c,l]. [cd1,cd2,cd3,cd4,cd5,cd6,cd7,cd8] = detcoef(c,l,[1 2 3 4 5 6 7 8]); figure(4) subplot(4,2,1) plot(cd1),title('detail subplot(4,2,2) plot(cd2),title('detail subplot(4,2,3) plot(cd3),title('detail subplot(4,2,4) plot(cd4),title('detail subplot(4,2,5) plot(cd5),title('detail subplot(4,2,6) plot(cd6),title('detail subplot(4,2,7) plot(cd7),title('detail subplot(4,2,8) plot(cd8),title('detail

coeff: level 1 cd1'),grid on coeff: level 2 cd2'),grid on coeff: level 3 cd3'),grid on coeff: level 4 cd4'),grid on

coeff: level 5 cd5'),grid on coeff: level 6 cd6'),grid on coeff: level 7 cd7'),grid on coeff: level 8 cd8'),grid on

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ZERO CROSSING REMOVAL base_corrected=ca2; y=base_corrected-zc; figure(5) plot(y),grid on title('Noise Free signal')

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DETECT R_PEAK y1=y; m1=max(y1)-max(y1)*.60; P=find(y1>=m1); % it will give two two points ... remove one point each P1=P; P2=[]; last=P1(1); P2=[P2 last]; for(i=2:1:length(P1)) if(P1(i)>(last+10)) last=P1(i); P2=[P2 last]; end end Rt=y1(P2); figure(6) plot(y1),grid on,hold on plot(P2,Rt,'*'); title('Rpos in downsampled signal');

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C

te R n t e

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P3=P2*4; Rpos=[]; for( i=1:1:length(P3)) range= [P3(i)-20:P3(i)+20]; m=max(A(range)); l=find(A(range)==m); pos=range(l); Rpos=[Rpos pos]; end Ramp=A(Rpos); figure(7) plot(A),grid on,hold on plot(Rpos,Ramp,'*'); title('Detected R peak in actual Signal'); R_peaks = length(Rpos)

%disp([num2str(R_peaks) ' peaks'])

R_peaks = 13

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A ter R Pe

Tr

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DETCET OT ERS

X=Rpos; y1=A; for(i=1:1:1)

for(j=1:1:length(X))

a=X(j)-100:X(j)-50; m=max(y1(a)); b=find(y1(a)==m); b=b(1); b=a(b);

ONSET fnd=0; for k=b-20:+1:b if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b-20:+1:b; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end

RON(i,j)=qon1(1); fnd; for k=b:+1:b+20 if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b:+1:b+20; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end ROF(i,j)=qon1(1);

P Pe a=Rpos(i,j)-100:Rpos(i,j)-10; m=max(y1(a)); b=find(y1(a)==m); b=b(1); b=a(b); Ppos(i,j)=b; Pamp(i,j)=m;

end

Dete t on a=Rpos(i,j)-50:Rpos(i,j)-10; m=min(y1(a)); b=find(y1(a)==m); b=b(1); b=a(b); Qpos(i,j)=b; Qamp(i,j)=m; %%%%% ONSET fnd=0; for k=b-20:+1:b if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b-20:+1:b; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end QON(i,j)=qon1(1); fnd; for k=b:+1:b+20 if((y1(k)0)) qon1=k;

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fnd=1; break end end if(fnd==0) Qrange=b:+1:b+20; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end QOF(i,j)=qon1(1);

S Dete t on a=Rpos(i,j)+5:Rpos(i,j)+50; m=min(y1(a)); b=find(y1(a)==m); b=b(1); b=a(b); Spos(i,j)=b; Samp(i,j)=m; %%%% onset off fnd=0; for k=b-5:+1:b if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b-20:+1:b; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end SON(i,j)=qon1(1); fnd=0; for k=b:+1:b+20 if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b:+1:b+20; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end SOFF(i,j)=qon1(1);

T Pe a=Rpos(i,j)+25:Rpos(i,j)+100; m=max(y1(a)); b=find(y1(a)==m); b=b(1); b=a(b);

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Tpos(i,j)=b; Tamp(i,j)=m; %%%% onset off fnd=0; for k=b-20:+1:b if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b-20:+1:b; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end TON(j,i)=qon1(1); fnd=0; for k=b:+1:b+20 if((y1(k)0)) qon1=k; fnd=1; break end end if(fnd==0) Qrange=b:+1:b+20; qon1=find(y1(Qrange)==max(y1(Qrange))); qon1=Qrange(qon1); end TOFF(j,i)=qon1(1); if(Tamp(i,j)6) k=1; figure; end

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end % Detected no of peaks R_peaks = length(Rpos) P_peaks = length(Ppos) T_peaks = length(Tpos) S_peaks = length(Spos) Q_peaks = length(Qpos) clc; flag=0; if(length(ELEVATED)>ceil(.8*length(Rpos))) disp('T inverted (MI Detected) with T inverted Logic') return; else flag=1; end R_peaks P_peaks T_peaks S_peaks Q_peaks

= = = = =

R_peaks = 13

P_peaks = 13

T_peaks = 13

S_peaks = 13

Q_peaks = 13

R_peaks = 13

length(Rpos) length(Ppos) length(Tpos) length(Spos) length(Qpos)

Generated by Foxit PDF Creator © Foxit Software http://www.foxitsoftware.com For evaluation only. P_peaks = 13

T_peaks = 13

S_peaks = 13

Q_peaks = 13

Published with MATLAB® 7.14